Welcome, lazlo 'n guest! John Jacob Niles is quite famous around these parts; I tried looking up a biography on him, but got tired before finding one that said whether one or both of his parents were of German descent. (Alex, you want to run across the street and look this up? ) He probably did pick it up from local songs, though. One of the sites had him singing, and I was reminded of another, perhaps not quite so well known, Kentucky folk singer: Jean Ritchie, who also sings (some) in a high-pitched unaccompanied voice, and who also felt it was important to preserve mountain music.

Anyway--I found this explanation by JJN about how he came to compose a particular song, and thought it priceless:
"I Wonder As I Wander grew out of three lines of music sung for me by a girl who called herself Annie Morgan. The place was Murphy, North Carolina,and the time was July, 1933. The Morgan family, revivalists all, were about to be ejected by the police, after having camped in the town square for some little time, coking, washing, hanging their wash from the Confederate monument and generally conducting themselves in such a way as to be classed a public nuisance. Preacher Morgan and his wife pled poverty; they had to hold one more meeting in order to buy enough gas to get out of town. It was then that Annie Morgan came out--a tousled, unwashed blond, and very lovely. She sang the first three lines of the verse of "I Wonder As I Wander". At twenty-five cents a performance, I tried to get her to sing all the song. After eight tries, all of which are carefully recorded in my notes, I had only three lines of verse, a garbled fragment of melodic material--and a magnificent idea. With the writing of additional verses and the development of the original melodic material, "I Wonder As I Wander" came into being. I sang it for five years in my concerts before it caught on. Since then, it has been sung by soloists and choral groups wherever the English language is spoken and sung."